source: trunk/kernel/libk/remote_busylock.c @ 563

Last change on this file since 563 was 563, checked in by alain, 3 years ago

Complete restructuration of kernel spinlocks.

File size: 4.6 KB
Line 
1/*
2 * remote_busylock.c - remote kernel busy-waiting lock implementation.
3 *
4 * Authors     Alain Greiner (2016,2017,2018)
5 *
6 * Copyright (c) UPMC Sorbonne Universites
7 *
8 * This file is part of ALMOS-MKH.
9 *
10 * ALMOS-MKH is free software; you can redistribute it and/or modify it
11 * under the terms of the GNU General Public License as published by
12 * the Free Software Foundation; version 2.0 of the License.
13 *
14 * ALMOS-MKH is distributed in the hope that it will be useful, but
15 * WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
17 * General Public License for more details.
18 *
19 * You should have received a copy of the GNU General Public License
20 * along with ALMOS-MKH; if not, write to the Free Software Foundation,
21 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
22 */
23
24#include <kernel_config.h>
25#include <hal_kernel_types.h>
26#include <hal_irqmask.h>
27#include <hal_special.h>
28#include <hal_remote.h>
29#include <thread.h>
30#include <remote_busylock.h>
31
32//////////////////////////////////////////////////////////////////////////////
33//                Extern global variables
34//////////////////////////////////////////////////////////////////////////////
35
36extern char               * lock_type_str[];    // allocated in kernel_init.c
37extern chdev_directory_t    chdev_dir;          // allocated in kernel_init.c
38
39
40////////////////////////////////////////////
41void remote_busylock_init( xptr_t   lock_xp,
42                           uint32_t type )
43{
44    // get remote lock cluster and local pointer
45    cxy_t        lock_cxy = GET_CXY( lock_xp );
46    busylock_t * lock_ptr = GET_PTR( lock_xp );
47
48    hal_remote_s32( XPTR( lock_cxy , &lock_ptr->ticket  ) , 0 );
49    hal_remote_s32( XPTR( lock_cxy , &lock_ptr->current ) , 0 );
50    hal_remote_s32( XPTR( lock_cxy , &lock_ptr->type    ) , type );
51
52#if DEBUG_BUSYLOCK
53    xlist_entry_init( XPTR( lock_cxy , &lock_ptr->xlist ) ); 
54#endif
55
56}
57
58////////////////////////////////////////////////
59void remote_busylock_acquire( xptr_t   lock_xp )
60{
61    reg_t      save_sr;
62    thread_t * this = CURRENT_THREAD;
63
64    // get remote lock cluster and local pointer
65    cxy_t        lock_cxy = GET_CXY( lock_xp );
66    busylock_t * lock_ptr = GET_PTR( lock_xp );
67
68    // enter critical section
69    hal_disable_irq( &save_sr );
70 
71    // get one ticket
72    uint32_t ticket = hal_remote_atomic_add( XPTR( lock_cxy , &lock_ptr->ticket ) , 1 );
73
74    // poll current until success
75    xptr_t current_xp = XPTR( lock_cxy , &lock_ptr->current );
76    while( hal_remote_l32( current_xp ) != ticket ) asm volatile ("nop");
77
78    // increment thread locks counter
79    this->busylocks++;
80
81    // save SR in lock descriptor
82    hal_remote_s32( XPTR( lock_cxy , &lock_ptr->save_sr ) , save_sr );
83
84    // memory barrier to update busylock and thread state
85    hal_fence();
86   
87#if DEBUG_BUSYLOCK
88uint32_t type = hal_remote_l32( XPTR( lock_cxy , &lock_ptr->type ) );
89if( (type != LOCK_CHDEV_TXT0) &&
90    (XPTR( local_cxy , this ) == DEBUG_BUSYLOCK_THREAD_XP) &&
91    ((uint32_t)hal_get_cycles() > DEBUG_BUSYLOCK) )
92{
93    xptr_t root_xp = XPTR( local_cxy , &this->busylocks_root );
94
95    // update thread list of busyslocks
96    xlist_add_last( root_xp , XPTR( lock_cxy  , &lock_ptr->xlist ) );
97
98    // display busylocks for the selected thread (acquire)
99    thread_display_busylocks( type , true ); 
100}
101#endif
102
103}  // end remote_busylock_acquire()
104
105///////////////////////////////////////////////
106void remote_busylock_release( xptr_t  lock_xp )
107{
108    thread_t * this = CURRENT_THREAD;
109
110    // memory barrier to update the protected object
111    hal_fence();
112
113    // get remote lock cluster and local pointer
114    cxy_t        lock_cxy = GET_CXY( lock_xp );
115    busylock_t * lock_ptr = GET_PTR( lock_xp );
116
117    // update lock state
118    hal_remote_atomic_add( XPTR( lock_cxy , &lock_ptr->current ) , 1 );
119
120    // decrement thread locks counter
121    this->busylocks--;
122
123    // memory barrier to update busylock and thread state
124    hal_fence();
125
126#if DEBUG_BUSYLOCK
127uint32_t type = hal_remote_l32( XPTR( lock_cxy , &lock_ptr->type ) );
128if( (type != LOCK_CHDEV_TXT0) && 
129    (XPTR( local_cxy , this ) == DEBUG_BUSYLOCK_THREAD_XP) &&
130    ((uint32_t)hal_get_cycles() > DEBUG_BUSYLOCK) )
131{
132    // remove lock from thread list of busyslocks
133    xlist_unlink( XPTR( lock_cxy  , &lock_ptr->xlist ) );
134
135    // display busylocks for the selected thread (release)
136    thread_display_busylocks( type , false );   
137}
138#endif
139                                 
140    // exit critical section
141    hal_restore_irq( hal_remote_l32( XPTR( lock_cxy , &lock_ptr->save_sr ) ) );
142 
143}  // end remote_busylock_release()
144
145
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